ARI SHAPIRO, HOST:
And Europe isn't the only place getting hit with searing heat this week. China is facing another week of extreme temperatures. In the U.S., Texas, California and the Central Plains states all have excessive heat warnings in effect. So to talk about this, we're joined by Laura Benshoff of NPR's climate team. Hey, Laura.
LAURA BENSHOFF, BYLINE: Good afternoon.
SHAPIRO: Extreme heat hitting a lot of places all at once. How direct is the link to climate change here?
BENSHOFF: This is exactly the pattern that scientists say plays out with climate change. Heat waves are getting more common, and they're getting more intense. Scientists are finding that some heat waves, like the record-breaking one in the Pacific Northwest last year, would be virtually impossible without human-caused climate change. And remember; this is what we're seeing with the planet having warmed about two degrees Fahrenheit since pre-industrial times. This trend is expected to just keep getting worse as global average temperatures rise. And in many places, temperatures alone aren't the only danger. It's also the humidity.
SHAPIRO: Speaking to you from here in Washington, D.C., I know how miserable humidity can feel, but explain why it's actually more dangerous than high heat alone.
BENSHOFF: So it has to do with our ability to sweat. You know, the basic idea is your body sweats. The sweat evaporates off your skin, and it cools our bodies in that process, right? But high humidity makes that more difficult. NPR spoke to Larry Kenney, a professor of physiology, about that. He has a lab at Penn State University where he cranks up the heat and humidity, and then he has people on a treadmill to see how their bodies respond. He says humidity has a big effect.
LARRY KENNEY: Only sweat that evaporates has any ability to cool the body. And so as the absolute humidity increases, when it gets close to the humidity of the sweat on the skin, it can no longer evaporate.
BENSHOFF: So basically, you can be covered in sweat, but if it's not evaporating, you're not getting any cooler. And out in the real world, the temperature might not seem that high, but if the humidity is super-high, it's still really dangerous.
SHAPIRO: So climate change is increasing heat waves. Is it also increasing humidity?
BENSHOFF: Studies are finding that it is. And that's because warmer air can hold more water vapor, which means more humidity. So as the climate warms, scientists say we need to pay attention not just to the overall temperature but something called the wet bulb temperature that takes humidity into account. And Kenney's lab recently found that the maximum wet bulb temperature that humans can endure is 88 degrees Fahrenheit at 100% humidity. He says even if you're just sitting in the shade, you're at risk of heatstroke and even death in those conditions.
KENNEY: People need to understand that heat is the most deadly of all weather-related fatalities - much more so than tornadoes, hurricanes, all other things combined - that it is dangerous and, in particular, it's dangerous to vulnerable populations like the elderly.
BENSHOFF: He says a good thing to keep tabs on is the heat index from the National Weather Service, which takes humidity into account.
SHAPIRO: Let's talk about the effort to address all of this because climate action seems to have stalled in the U.S. at least. Democrats were hoping to pass major climate spending, but last week Senator Joe Manchin of West Virginia pulled his support. What options do Democrats have right now?
BENSHOFF: You know, they're still hoping to push climate spending through. This is billions of dollars for things like subsidies for electric cars and renewable energy. And Democrats have argued that energy costs are a big part of inflation right now. And so these incentives could help with those costs in the long term. But Manchin has said he wants to see what happens with inflation before making the deal. So right now a big spending package is off the table. Some hope that, you know, he'll come back to the table, these subsidies could get through later or they could be split up and passed on a piecemeal basis. Now, the White House released a statement last week saying if the Senate wouldn't act on climate change, then President Biden would use executive orders to further his climate agenda.
SHAPIRO: All right. That's NPR's Laura Benshoff. Thanks for your coverage, Laura.
BENSHOFF: Thank you so much. Transcript provided by NPR, Copyright NPR.
